Energy efficient hydraulic system topologies for load-haul-dump machine

Abstract

Diesel engine powered non-road mobile machines have been noted to be a considerable source of pollutant emissions. It is one reason for a growing trend where the powertrains of heavy mobile machinery including diesel engines are being replaced with hybrid or fully electric powertrains. Battery-powered non-road mobile machines require that more energy efficient hydraulic topologies are developed for the machines. Therefore, in this research novel hydraulic topologies were compared to evaluate efficiency characteristics of them in a load-haul-dump machine application. A system level simulation model of a load-haul-dump machine was developed, and its energy efficiency was compared with a model of a diesel-powered machine by driving a test cycle in a virtual mine with both models. Energy efficiencies of three different hydraulic bucket system topologies - load-sensing, direct driven hydraulics, and tandem pump system - were compared. The results of the test cycle emphasized the advantages of an electric powertrain. Especially, the energy recovery in the downhill, where over 50 percent of the total energy used for other sections of the driving cycle were regenerated to the battery. The direct driven hydraulics in the steering system reduced the energy consumption. In the analysis of the bucket systems, the direct driven hydraulic system had about 60 percent and the tandem pump system had about 50 percent smaller energy consumption than the load-sensing system